AFAIK, there is no standard way to achieve this.
But this can be done programmatically with no apparent troubles.
In this case, I would recommend you to create a timer job, and based on settings stored in detached "configuration" list - change permissions on particular folders every night (or more often, if needed).
I assume, the "configuration" list should include: a
Folder lookup column, a
Start date and an
End date date columns, and finally,
Denied Groups column of type 'Person or group'.
In the timer job, you should instantiate the particular SPWeb object, connect to the configuration list, and retrieve all items where
Start date or
End date equal to the current date. I'd recommend you to use CAML query and SPList.GetItems method to retrieve the rules.
Then, for each rule, you should retrieve the corresponding folder element from the primary list, and change it's permissions respectively to the rule contents.
I would estimate, it would take about 1-2 days, to implement all this functionality from scratch, depending of your experience with timer jobs and permissions.